It’s not just moms who are staying home with the kids in greater numbers. More dads are doing it, too.

In 2012, there were 2 million U.S. fathers who lived with their children but did not work outside the home, nearly double the 1.1 million in 1989, the first year for which data are available, according to a Pew Research Center report released Thursday. The number of “stay-at-home dads” actually peaked in 2010, at 2.2 million.

Of America’s stay-at-home parents, 16% are now fathers, and 84% are mothers, compared with 10% and 90% in 1989.

Pew said the recent pick-up in stay-at-home fathers is due to high unemployment tied to the recession, which spanned from late 2007 to mid-2009. But what’s driving the long-term rise in stay-at-home fathers may not be the economy’s vicissitudes so much as increased willingness among men to play the role of primary caregiver.

Roughly one in five stay-at-home fathers (21%, or 425,000 dads) say the main reason they’re home is to care for their home and family. That is a four-fold increase from just 5% in 1989, Pew said.

Pew analyzed U.S. Census Bureau data on men 18 to 69 years old who were living with their own children under 18 (whether biological, step- or adopted-children) and who were not employed for pay at all outside the home over the prior year. (Pew excluded fathers not living with any of their children.)

The vast majority of stay-at-home parents are still, of course, mothers. An earlier Pew report found that, after decades of decline, the share of mothers staying at home with children has risen recently.

A big chunk of stay-at-home fathers simply can’t find a job. About 23% of stay-at-home dads said this is why they were home, up from 15% in 1989.

Also: Like stay-at-home mothers, stay-at-home fathers tend to be less financially secure and educated.

A disturbing finding in Pew’s report is that roughly half (47%) of stay-at-home dads are officially poor, compared with just 8% of working fathers (defined as those who have had any work over the past year, even part-time). While the percentage of stay-at-home moms who are poor is also high, it’s considerably lower at 34%.

The share of stay-at-home fathers with less than a high-school diploma is 14%, compared with 7% for fathers with some college. While the share of stay-at-home fathers with bachelor’s degrees has tripled, the actual numbers remain small: from 1% in 1989 to 3% in 2012.

Black fathers who live with their children are the most likely to be stay-at-home fathers, compared with Hispanics and Asian-Americans, and especially white fathers—partly due to higher joblessness rates.

Still, the reasons why U.S. dads stay home and don’t work are slowly shifting.

In 2012, 35% of stay-at-home dads cited illness or disability as the main reason for being home, a big drop from 56% in 1989. The shares of stay-at-home dads citing being in school or retired also dropped.

Meanwhile, those saying they’re home either for their kids, or because of joblessness, is rising. Roughly equal shares of working fathers and mothers in the U.S. now say they would prefer to be at home raising kids, but need to work to get income.

“The rising number of dads who are home primarily to care for their family has driven the long-term growth in ‘stay-at-home dads’,” said Pew senior researcher Gretchen Livingston.

The Census Bureau, which uses a more restrictive definition of “stay-at-home” dad—the children must be under 15, the couple married, and the father needs to say he’s home for a year to care for kids—puts their number much lower, at 214,000, versus Pew’s 2 million.

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